Serial printing mechanism

ABSTRACT

In a serial printing mechanism for calculating machines, a type drum bearing a plurality of rows of types rotates for selection of the types whereas a cylinder has a plurality of projections disposed in the form of a helix and axially aligned with the rows of types. Impression means moves the cylinder towards the drum to cause one of the projections to strike against the selected type and to rotate the cylinder step by step to bring the projector sequentially into the striking position.

United States Patent Bovio [451 Aug. 15, 1972 SERIAL PRINTING MECHANISM 2,910,936 1 1/1959 Christoff et a1. ..101/93 [72 Inventor: Dario Bnvio, lvrea Italy 3,313,48l 4/l967 KOl'ldUl' 61: al. ..235/6l PB 3,384,301 5/1968 Berkman et a1 ..235/60 R Assigfleel Ing. Olivetti 8: C., S.p.A., lv 3,455,237 7/1969 Trab ..101/91 Italy 3,461,797 8/1969 Trab et a1. ..l01'/9l X J et R [2]] Appl. No.: 47,337 Primary Examiner-William B. Penn Attorney--Birch, Swindler, McKie & Beckett [30] Foreign Application Priority Data 57] ABSTRACT June 27, 1969 Italy ..52405 A/69 In a serial printing mechanism for calculating [52] U S Cl 01/93 C machines, a type drum bearing a plurality of rows of [51] H22 types rotates for selection of the types whereas a [58] Fieid '6 j R 92 cylinder has a plurality of projections disposedin the 235/60 i 1 form of a helix and axially aligned with the rows of types. Impression means moves the cylinder towards the drum to cause one of the projections to strike [56] References Cited against the selected type and to rotate the cylinder UNITED STATES PATENTS sttlep bykstep to hring the projector sequentially into t St 1 t 2,858,536 1011958 Johnston ..101/93 c e n ,968 12/1959 Witt et a]. 101/93 C 4 Claims, 7 Drawing Figures PATENTEDM E 1 5 I97? 3 683. 800

sum 1 or 2 INVENTOR. ILARIO BOVIO CROSS REFERENCE TO RELATED APPLICATION Applicant claims priority from corresponding Italian BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial printing mechanism for typewriters, teleprinters, calculators, accounting machines and similar officer machines, including a type drum bearing a plurality of rows of types and rotatable for selection of the types.

2. Description of the Prior Art Various serial printing mechanisms are known. One of these mechanisms includes a type head and a hammer which can be shifted jointly step by step with respect to a support for the paper. This mechanism is slow and is moreover complex because of the escapement mechanism which controls the transverse movement of the head and the hammer with respect to the support for the paper.

Another serial printing mechanism includes a drum bearing a plurality of rows of types and rotatable continuously, and a hammer actuated by an electromagnet for printing on the fly, the hammer being shiftable transversely with respect to the drum. In the event of the mechanism including a plurality of hammers, each hammer is transversely fixed so as to be able to effect the scanning of the types in a single row. This mechanism, however, is complex and too costly for simple office machines.

Both of these mechanisms are very noisy because of the impact of the hammer on the type. In order to reduce this noise, there has already been proposed a parallel printing mechanism in which the impression support is constituted by a rotatable cylinder the circumferential points of which perform a cycloidal movement with respect to a series of type wheels, each of which is selected before the striking of the cylinder against the wheels themselves. This mechanism, however, is very complex and costly and is not applicable to simple office machines.

SUMMARY OF THE INVENTION The technical problem that the present invention seeks to solve is that of providing a serial printing mechanism constituted by simple mechanical parts having only simple rotary movements, so as to reduce substantially the noise of the mechanism.

According to the invention, there is provided a serial printing mechanism for typewriters, teleprinters, calculators, accounting machines and similar office machines, including a type drum bearing a plurality of rows of types and rotatable for selection of the types, a cylinder having a plurality of projections disposed in the form of a helix and axially aligned with the rows of types, impression means being adapted to move the cylinder towards said drum to cause one of the projections to strike against the selected type and to rotate the cylinder step by step to bring the projections sequentially into the striking position.

BRIEF DESCRIPTION OF THE DRAWING A preferred embodiment of the invention is described hereinafter and shown in the accompanying drawings, in which:

FIG. 1 is a plan view of a numerical printing mechanism embodying the invention;

FIG. 2 is a section on the line "-11 of FIG. 1;

FIG. 3 is the section of FIG. 2 in a working position;

FIG. 4 is a partial section on the line IV-IV of FIG. I;

FIG. 5 is a plan view of a variant of the mechanism embodying the invention;

FIG. 6 is a partial section on the line VIVI of FIG. 5; and

FIG. 7 is a diagram of the path of an impression element of the mechanism in accordance with the two embodiments of FIGS. 1 and 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The printing mechanism is fitted here to a calculating machine of the type described in US. Pat. Application Ser. No. 12,688, filed Feb. 19, 1970, in the name of Nicolo Giolitti, et al which is adapted to supply in series the data representing an amount to be printed. More particularly, US. Pat. Application No. 12,688 describes a calculating machine adapted to perform additions, substractions and total taking operations by handling the amounts order by order. The figures of an amount to be printed are serially represented by selectively setting one of a plurality of setting elements, which cooperate with a V-shaped cam edge carried by a drum which is cyclically rotated by the machine motor. The engagement of the V-shaped cam edge and the setting element causes the drum to be differentially shifted axially from a central or rest position under the direction of the setting element. Movement of the drum in one direction presents the figures 4 to 0, and movement in the opposite direction presents the figures 5 to 9. At the end of each cycle, the drum is restored to the central position. Obviously, the various characters to be printed can be generated by differentially setting in succession a character presenting member in any other known manner. The printing mechanism includes a drum 286 (FIG. 1) slidable axially on a shaft 143, but angularly fast therewith by means of two keys 290 (FIG. 4). The drum 286 (FIG. 1) is provided with a series of annular grooves 291 in engagement with a pinion 292 which is fixed to a shaft 293 rotatable in two side pieces 294 of the frame of the machine. On the shaft 293 there is moreover fixed a drum 296 bearing in relief thereon eight rows of ten types 297 for the digits from zero to nine. The above mentioned elements of the mechanism are shown in the cited US. Pat. Application No. 12,688, drum 286 being integral with the drum carrying the V-shaped cam.

On the depression of an operative key of the machine, the main shaft 61 (FIG. 4) turns anticlockwise, producing clockwise rotation of the shaft 143 by means of the gears 141, 142. At each revolution of the shaft 143, the machine transfers to the printing mechanism one digit of the amount to be printed, beginning with that of the lowest order. As described in the Patent Application referred to, the drum 286 (FIG.

l) is shifted upwardly each time for a distance such that the pinion 292 turns by from half a pitch up to four and a half pitches in the case where the machine transfers a digit from four to zero to the mechanism, causing the shaft 293 (FIG. 2) to rotate anticlockwise correspondingly. On the other hand, the drum 286 (FIG. 1) is shifted downwardly for a distance such that the pinion 292 turns by from half a pitch up to four and a half pitches in the case where the machine transfers a digit from five to nine to the mechanism, causing the shaft 293 (FIG. 2) to rotate clockwise correspondingly. The drum 296 rotates together with the shaft 293 and, therefore, at the beginning of each cycle of the shaft 143 (FIG. 3), positions each time on the printing line the type 297 selected in a row, commencing from the one on the right (FIG. 1

The drum 296 is adapted to co-operate with an impression support constituted by a cylinder 298 rotatably mounted on a shaft 299 eccentric and integral with a shaft 299 rotatable in the side pieces 294. The cylinder 298 carries in relief thereon eight projections 300 307 of elastic material, for example rubber, which are disposed at the periphery of the cylinder 298 in the form of a helix. The projections 300 307 are substantially in the form of rectangular parallelepipeds and are spaced axially in accordance with the printing step. Each of the projections 300 307 is adapted to co-operate with a row of types 297 on the drum 296, the first projection 300 (FIG. 1) with the first row of types 297 starting from the right and so on in the case of the other projections up to the projection 307, which is adapted to co-operate with the first row of types 297 starting from the left.

The drum 296 (FIG. 2) normally presents in front of or facing the cylinder 298 the space between the types of the digit four and the digit five. The cylinder 298, in turn, normally presents to the drum 296 the projections 300 and 307, which are inclined symmetrically with respect to a horizontal plane extending through the center of the shaft 293. Between the drum 296 and the cylinder 298 there is inserted'a strip of paper 32 and between this strip of paper and the drum 296 there is an inked ribbon 308.

At the left-hand end of the cylinder 298 (FIG. 1) there is fixed a gear 309 which is in mesh with a gear 310 (FIG. 2) having internal teeth integral with a frame 311 fast with the left-hand side piece 294 (FIG. 1). As will be seen hereinafter, at each revolution of the shaft 299 the gear 309 (FIG. 2) rotates inside the gear 310 and engages by means of its teeth the corresponding spaces of the gear 310. The latter gear has two teeth more than the gear 309 and, therefore, at each revolution, for example anticlockwise, of the shaft 299 the gear 309 performs a clockwise rotation equal to two pitches. The projections 300, 307 are therefore dis- .tributed at the periphery of the cylinder 298 in accordance with an angular pitch equal to two steps of the gear 309.

During the rotation of the shaft 299, each point of the pitch circle of the gear 309 describes a cycloidal path. The outer edges of the projections 300 307 are substantially tangent to said pitch circle and therefore their path is substantially cycloidal.

At the right-hand end of the shaft 299 (FIG. 1) there is fixed a gear 312 which is in mesh with a gear 313 fixed on a shaft 314 rotatable in the right-hand side piece 294. A bevel gear 315 fixed on the shaft 314 is in mesh with another gear 316 (FIG. 4) fixed to the main shaft 61 of the machine.

The printing mechanism operates in the following manner.

At each rotation of the shaft 61 (FIG. 4), the shaft 299 (FIG. 2) performs a complete revolution anticlockwise through the medium of the gears 316, 315, 313 and 312 (FIG. 1), while the gear 309 revolves inside the gear 310 and performs each time a clockwise rotation equal to two pitches, causing the projections 300 307 to advance by one step in the same sense. More particularly, in correspondence with the first revolution of the shaft 299, the projection 300 describes a substantially cycloidal path shown on a larger scale and indicated by the reference 290 in FIG. 7 and having its cusp on the drum 296, which in the meantime has positioned in front of the cylinder 298 the type 297 selected in the first row starting from the right (FIG. 1). The projection 300 moves up to the selected type 297 in correspondence with the first half of the revolution of the shaft 299, making contact to the point of being compressed against this type (FIG. 3) and thus permitting the printing of the character on the strip of paper 32 by pressure. During the second half of the revolution of the shaft 299, the projection 300 moves away from the drum 296 until it reaches the angular position which is represented in FIG. 2 by the projection 307.

At the beginning of the second revolution of the shaft 61 and the shaft 143, the machine transfers the second digit to the mechanism as described in the aforementioned application and the drum 296 positions itself angularly in such manner that the second row of types 297 from the right (FIG. 1) presents the selected type to the cylinder 298. Thereafter, the cylinder 298 brings up to the drum 296 the projection 30], which starts from the angular position represented in FIG. 2 by the projection 300. The digit of the order immediately higher than that printed before is thus impressed on the paper 32. The projection 301 then moves away from the drum 296 and reaches the angular position which is represented in FIG. 2 by the projection 307. The rotation of the shaft 299 continues until the digit of the highest order has been transferred by the machine to the printing mechanism.

According to a variant of the mechanism, the gear 3I0 is formed in a frame 3I7 (FIG. 5) in a seat of which there is adapted to rotate a disc 318 (FIGS. 5 and 6) fixed eccentrically on the shaft 299a. In turn the shaft 299 is mounted eccentrically on the disc 318. The frame 317 is moreover provided with a pin 319 which is adapted to turn and slide in a slot 32I in the left-hand side piece 294.

At each anticlockwise revolution of the shaft 299 (FIG. 6), the eccentricity of the disc 3I8 with respect to the shaft 299 causes the frame 317 to oscillate about the pin 319 and at the same time causes the pin 319 to advance within the opening 321, together with the frame 317, first to the left and then, from the position reached, to the right. The eccentricity of the sleeve 299a (and hence of the cylinder 298) with respect to the shaft 299 is greater than that of the disc 318.

In turn, at each revolution of the shaft 299, the eccentricity of the shaft 299a with respect to the shaft 299 causes the gear 309 to revolve inside the gear 310 and causes the teeth of the gear 309 to engage the corresponding spaces of the gear 310 during the described movement of the frame 317, as a result of which each point of the pitch circle of the gear 309 and, therefore, also the projections 300 307 describe a cycloidal path with respect to the frame 317 at each revolution of the shaft 299.

After each revolution of the shaft 299, the frame 317 readopts the position shown in the drawing, while the gear 309, and with it the cylinder 298, turn in the opposite sense to the rotation of the shaft 299 by an amount equal to the angular pitch of the projections 300 307.

The path of the outer edges of the projections 300 307 with respect to the drum 296 is the resultant of a substantially cycloidal path of the edges themselves with respect to the frame 317 and of the movement of oscillation and advance of the latter. The first path is practically that indicated by the reference 290 in FIG. 7, while the resultant path is indicated by the reference 295 in the same drawing. The latter path has a very pointed cusp and, therefore, each of the projections 300 307 can engage the selected type with a final travel which is substantially rectilinear and perpendicular to the plane containing said type. The path 295 followed by the projections 300 307 ensures that the engagement of each projection with the selected type takes place without any sliding or dragging action and the printing of the character on the sheet of paper 308 interposed therefore takes place without any blurring.

What I claim is:

l. A serial printing mechanism for typewriters, teleprinters, calculators, accounting machines and similar office machines comprising in combination:

a type drum bearing a plurality of rows of types,

means cyclically operable for selectively rotating said type drum for sequential selection of said types on individual rows,

rotatable cylinder means having a plurality of projections disposed in the form of a helix and axially aligned with said rows of types, said cylinder means also being laterally movable between a first position wherein a selected one of said projections strikes against a selected one of said types and a second position wherein said projections are spaced from said types, and

impression means engaging said cylinder means for rotatably and laterally moving said cylinder means so that said selected projection strikes against said selected type and said cylinder means is rotated step by step to bring said projections sequentially into position for striking said types.

2. A mechanism according to claim 1 wherein said impression means comprises:

a shaft rotatable in a support,

a first eccentric carried by said shaft, said cylinder means being mounted on said first eccentric and in engagement therewith so that rotation of said shaft causes said first eccentric to move said cylinder means laterally between said first and second positions,

a firstgear fixedly attached to and coaxial with said shaft and havn ext rnal teet ,and a second gear disgose about sa id first gear and having internal teeth meshing with said external teeth of said first gear, the ratio between the number of teeth on said first gear and'the number of teeth on said second gear being such that for each revolution of said shaft said first gear turns inside said second gear such an amount as to move said projections one step corresponding to the distance between two adjacent projections, whereby said projections move in cyclic paths as said cylinder means is concurrently rotated and moved laterally.

3. A mechanism according to claim 6 further comprising:

a movable frame carrying said second gear, and

a second eccentric fixed eccentrically on said shaft and engaging said frame, said second eccentric being so oriented with respect to said first eccentric as to move said frame during movement of said cylinder means to deform the cycloidal movement of said projections so that the apex of the cycloidal movement of said selected projection is lengthened and the final travel of said selected projection toward engagement with said selected said type is substantially rectilinear and perpendicular to the plane of said selected type.

4. A mechanism according to claim 3 wherein the movement of said frame is defined by a pin and slot connection attached to said support, and wherein the eccentricity of said first eccentric with respect to said shaft is greater than the eccentricity of said second eccentric with respect to said shaft. 

1. A serial printing mechanism for typewriters, teleprinters, calculators, accounting machines and similar office machines comprising in combination: a type drum bearinG a plurality of rows of types, means cyclically operable for selectively rotating said type drum for sequential selection of said types on individual rows, rotatable cylinder means having a plurality of projections disposed in the form of a helix and axially aligned with said rows of types, said cylinder means also being laterally movable between a first position wherein a selected one of said projections strikes against a selected one of said types and a second position wherein said projections are spaced from said types, and impression means engaging said cylinder means for rotatably and laterally moving said cylinder means so that said selected projection strikes against said selected type and said cylinder means is rotated step by step to bring said projections sequentially into position for striking said types.
 2. A mechanism according to claim 1 wherein said impression means comprises: a shaft rotatable in a support, a first eccentric carried by said shaft, said cylinder means being mounted on said first eccentric and in engagement therewith so that rotation of said shaft causes said first eccentric to move said cylinder means laterally between said first and second positions, a first gear fixedly attached to and coaxial with said shaft and having external teeth, and a second gear disposed about said first gear and having internal teeth meshing with said external teeth of said first gear, the ratio between the number of teeth on said first gear and the number of teeth on said second gear being such that for each revolution of said shaft said first gear turns inside said second gear such an amount as to move said projections one step corresponding to the distance between two adjacent projections, whereby said projections move in cyclic paths as said cylinder means is concurrently rotated and moved laterally.
 3. A mechanism according to claim 6 further comprising: a movable frame carrying said second gear, and a second eccentric fixed eccentrically on said shaft and engaging said frame, said second eccentric being so oriented with respect to said first eccentric as to move said frame during movement of said cylinder means to deform the cycloidal movement of said projections so that the apex of the cycloidal movement of said selected projection is lengthened and the final travel of said selected projection toward engagement with said selected said type is substantially rectilinear and perpendicular to the plane of said selected type.
 4. A mechanism according to claim 3 wherein the movement of said frame is defined by a pin and slot connection attached to said support, and wherein the eccentricity of said first eccentric with respect to said shaft is greater than the eccentricity of said second eccentric with respect to said shaft. 